Iraqi National Journal of Earth Science

Abstract

It was claimed that the studied plant did not perform as expected. A careful investigation was carried out to troubleshoot any inconveniences. Many visits to plant site and discussion with managers and operators were made. A series of tests on samples taken from different sites in the river for various quality parameters such as pH, total solids TS, total dissolved solids TDS, electrical conductivity EC, Turbidity, nitrates NO3, phosphates PO4 , total plate bacterial count TPC, and algae were conducted .
The results revealed that the plant suffered a lot of problems. The plant acted as a passing through units. No significant change could be detected in received and treated water characteristics. Maintenance of various units were rarely practiced, and if it was done it would take long time. Pretreatment by alum was not carried out. This would complicate settling of flocs in subsequent units and might lead to growth of microorganisms.
As the plant located downstream a big impoundment lake, the incoming water characteristics were relatively acceptable and bear a sign of eutrophied water particularly phosphates and nitrates. Patches of algae could be seen adhered to sedimentation tank walls.
Backwashing of filters was done by air scour only through the recent 20 years. This led to loss of fines and cracks in filter bed. Gradation of media grains and the depth of sand layer were not adequate. Acid loss of used media amounted to 6.3% which was excessive and beyond authorized criteria
Removal of algae and bacteria was low as filter medium pores were relatively Large due to loss of fines and due to possible contamination.